Two groups say they''ll sue BP PLC for killing endangered species in the Gulf of Mexico by failing to stop the oil spill and by using dispersants under water and on the surface, according to the Associated Press. The Southern Environmental Law Center and Defenders of Wildlife on Tuesday sent BP a required 60-day notice that they plan to sue under the Endangered Species Act. Attorney Catherine Wannamaker says they want to make sure that BP is held accountable for all the losses that may occur, and for restoring endangered species. By the most conservative estimate, 7 million gallons of crude have spilled into the Gulf of Mexico after a BP-operated offshore drilling rig exploded more than a month ago and killed 11 workers. At least three environmental lawsuits have been filed under the National Environmental Policy Act, which doesn''t require prior notice.